Topic
  • 5 replies
  • Latest Post - ‏2010-12-07T15:30:41Z by MichaelSternberg
Derf
Derf
9 Posts

Pinned topic Question about locked/changing files

‏2010-11-16T18:11:25Z |
I have a 700GB mail datastore (consisting of millions of files) in a folder on my client. (basically just E:\MAILBOX... To move this across from client to server at Gb will take about 4 hours, I figure. Do I need to put the application to sleep during this 4 hour (or whatever) period? (or does FB handle this?).

If we go full first time, incremental forever, will I also have to pause or shutdown my application during the FB backup?

Fred
Updated on 2010-12-07T15:30:41Z at 2010-12-07T15:30:41Z by MichaelSternberg
  • MichaelSternberg
    MichaelSternberg
    24 Posts

    Re: Question about locked/changing files

    ‏2010-11-19T16:13:11Z  
    No, you don't need to put application to sleep for 4 hours. FastBack performs so-called "hot" snapshot. Applications are instructed to stop for few moments at beginning of snapshot, so all writes, that belong to currently performed transactions, will be written to disk and volume, that is being backed up, will reach "consistent" state. After that snapshot will begin, while all applications, that perform reads or writes to that volume, will continue to work as usual. Snapshot, that will be created, will contain exact and consistent image of volume as it was at beginning of snapshot.

    "Incremental forever" means that all snapshots will contain deltas from previous ones and, therefore, will be very fast and small. If you will perform shutdown of computer during snapshot - this snapshot will be aborted, but when computer will boot up again and next snapshot will run - it will back up only changes since previous successful snapshot, means it will be incremental.

    And one additional point - FastBack is completely agnostic to number of files on backed up volume. It may a single file of 2TB or zillions of files, each one of 5KB, it doesn't matter to FastBack and does not affects any resources it takes.
  • Derf
    Derf
    9 Posts

    Re: Question about locked/changing files

    ‏2010-11-24T14:55:50Z  
    No, you don't need to put application to sleep for 4 hours. FastBack performs so-called "hot" snapshot. Applications are instructed to stop for few moments at beginning of snapshot, so all writes, that belong to currently performed transactions, will be written to disk and volume, that is being backed up, will reach "consistent" state. After that snapshot will begin, while all applications, that perform reads or writes to that volume, will continue to work as usual. Snapshot, that will be created, will contain exact and consistent image of volume as it was at beginning of snapshot.

    "Incremental forever" means that all snapshots will contain deltas from previous ones and, therefore, will be very fast and small. If you will perform shutdown of computer during snapshot - this snapshot will be aborted, but when computer will boot up again and next snapshot will run - it will back up only changes since previous successful snapshot, means it will be incremental.

    And one additional point - FastBack is completely agnostic to number of files on backed up volume. It may a single file of 2TB or zillions of files, each one of 5KB, it doesn't matter to FastBack and does not affects any resources it takes.
    thanks...

    How does FB tell the applications to stop writing? (does the client tell the local OS automatically, or do I have to tell my mail server, ETC to pause via a script?).

    Also, related to my previous question about the 4 hours, does TSM cache all the changes during that 4 hour time period so it gets a consistent backup? (there could be a ton of data changed over the 4 hour period)
  • MichaelSternberg
    MichaelSternberg
    24 Posts

    Re: Question about locked/changing files

    ‏2010-12-06T08:12:04Z  
    • Derf
    • ‏2010-11-24T14:55:50Z
    thanks...

    How does FB tell the applications to stop writing? (does the client tell the local OS automatically, or do I have to tell my mail server, ETC to pause via a script?).

    Also, related to my previous question about the 4 hours, does TSM cache all the changes during that 4 hour time period so it gets a consistent backup? (there could be a ton of data changed over the 4 hour period)
    FastBack "speaks" with applications using Virtual Shadow Copy (VSS) framework. Most of modern applications implements a "VSS writer" and able to communicate with backup applications such as FastBack. For legacy applications, that are not aware of VSS, FastBack supports running scripts, supplied by customer, before and after snapshot start.

    FastBack provides consistency of snapshot using Copy-On-Write mechanism. Once snapshot is started each write, directed to volume that is being backed up, is intercepted, existing data from the disk is being backed up and intercepted write is allowed to proceed. Also, location of this write is remembered by FastBack in order to be backed up in next incremental snapshot.
  • Derf
    Derf
    9 Posts

    Re: Question about locked/changing files

    ‏2010-12-06T17:08:48Z  
    FastBack "speaks" with applications using Virtual Shadow Copy (VSS) framework. Most of modern applications implements a "VSS writer" and able to communicate with backup applications such as FastBack. For legacy applications, that are not aware of VSS, FastBack supports running scripts, supplied by customer, before and after snapshot start.

    FastBack provides consistency of snapshot using Copy-On-Write mechanism. Once snapshot is started each write, directed to volume that is being backed up, is intercepted, existing data from the disk is being backed up and intercepted write is allowed to proceed. Also, location of this write is remembered by FastBack in order to be backed up in next incremental snapshot.
    thanks...

    Ok, i'm dealing with a legacy app... so for a test of how long the pre-consistency period takes, would
    it make sense to fire off an email from the pre-consistency, and another AFTER, so I can tell how long
    my application needs to sit still? (use postie and send an email before/after via the script).

    Also, would it make sense to NOT WORRY about it the first backup (as it is full backup FIRST time, then
    "Incremental Forever" after that... and NOT use the first backup, but rely on the subsequent snapshots
    (as they will take place much faster). That way I wouldn't even have to shut my mail application down AT
    ALL for the first big/long backup... ??
  • MichaelSternberg
    MichaelSternberg
    24 Posts

    Re: Question about locked/changing files

    ‏2010-12-07T15:30:41Z  
    • Derf
    • ‏2010-12-06T17:08:48Z
    thanks...

    Ok, i'm dealing with a legacy app... so for a test of how long the pre-consistency period takes, would
    it make sense to fire off an email from the pre-consistency, and another AFTER, so I can tell how long
    my application needs to sit still? (use postie and send an email before/after via the script).

    Also, would it make sense to NOT WORRY about it the first backup (as it is full backup FIRST time, then
    "Incremental Forever" after that... and NOT use the first backup, but rely on the subsequent snapshots
    (as they will take place much faster). That way I wouldn't even have to shut my mail application down AT
    ALL for the first big/long backup... ??
    I'm not quite catching why do you need to send e-mail before and after consistency point. What application we are talking about ? I believe there are some scripts that come with FastBack installation that deal with various applications like Oracle, DB2, Domino, MSSQL and so on.. If script for your application is not supplied you should refer to it's documentation on how to quiesce it. Please check supplied scripts for hints on how to write them. If your application doesn't supplies mechanism for quiescing, then the simplest solution will to stop the application before consistency point and start it after that, again, via scripts - providing that the application supports "stop" and "start" events (e.g. service in Windows or daemon in *nix).

    You can rely on first full backup (if it was finished successfully) in the same way as you can rely on following incremental backups. But you will have to quiesce your mail application (to make it to flush all transactions to disk) for all backups, never mind it was the first full or following incrementals. Also, time of your application to be down (quiesced) doesn't differ for first full backup or for following incrementals. So the answer is no, there is no difference for you between first full backup and following incrementals apart time it takes to perform the backup. Of course the first full will take much more time, but your application will be able to work during it as usual - and the snapshot will be consistent and reflect state of volume as it was at backup start, or more exactly - at consistency point of time.